linux-kernel - Re: [PATCH 0/6] Move pKVM ownership state to hyp

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Message-ID: <864iztnsa6.wl-maz@kernel.org>
Date: Sun, 16 Mar 2025 11:12:17 +0000
From: Marc Zyngier <maz@...nel.org>
To: Quentin Perret <qperret@...gle.com>
Cc: Oliver Upton <oliver.upton@...ux.dev>,
	Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Vincent Donnefort <vdonnefort@...gle.com>,
	linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/6] Move pKVM ownership state to hyp_vmemmap

On Thu, 27 Feb 2025 00:33:04 +0000,
Quentin Perret <qperret@...gle.com> wrote:
> 
> Hi all,
> 
> This series moves the hypervisor's ownership state to the hyp_vmemmap,
> as discussed in [1]. The two main benefits are:
> 
>  1. much cheaper hyp state lookups, since we can avoid the hyp stage-1
>     page-table walk;
> 
>  2. de-correlates the hyp state from the presence of a mapping in the
>     linear map range of the hypervisor; which enables a bunch of
>     clean-ups in the existing code and will simplify the introduction of
>     other features in the future (hyp tracing, ...)
> 
> Patch 01 is a self-sufficient cleanup that I found thanks to patch 05.
> Patches 02-04 implement the aforementioned migration of the hyp state
> to the vmemmap. Patches 05 and 06 are cleanups enabled by that
> migration.
> 
> Patches based on 6.14-rc4, tested on Qemu.
> 
> Thanks!
> Quentin
> 
> [1] https://lore.kernel.org/kvmarm/Z79ZJVOHtNu6YsVt@google.com/
> 
> Fuad Tabba (1):
>   KVM: arm64: Track SVE state in the hypervisor vcpu structure
> 
> Quentin Perret (5):
>   KVM: arm64: Use 0b11 for encoding PKVM_NOPAGE
>   KVM: arm64: Introduce {get,set}_host_state() helpers
>   KVM: arm64: Move hyp state to hyp_vmemmap
>   KVM: arm64: Defer EL2 stage-1 mapping on share
>   KVM: arm64: Unconditionally cross check hyp state
> 
>  arch/arm64/include/asm/kvm_host.h        |  12 +--
>  arch/arm64/kvm/hyp/include/nvhe/memory.h |  35 ++++++--
>  arch/arm64/kvm/hyp/nvhe/hyp-main.c       |   4 -
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c    | 106 ++++++++++++-----------
>  arch/arm64/kvm/hyp/nvhe/pkvm.c           |  54 ++++++++++--
>  arch/arm64/kvm/hyp/nvhe/setup.c          |  10 ++-
>  6 files changed, 147 insertions(+), 74 deletions(-)
> 

Reviewed-by: Marc Zyngier <maz@...nel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.